I have heard of Sega's associations with the real Yakuza. One story I heard is Sega were headhunting a certain employee who wanted to work for Nintendo, so Sega threatened... or kidnapped and theatened that employers family in order for them to choose Sega.
Can't recall how it all ended. I think he ended up with Nintendo and no one got hurt.
I don't think that one is SEGA's.
Their yakuza is for arcade business, not console business.
While Nintendo was in arcade business (sucessfully too with Donkey Kong), they left arcade business when Famicom (NES) was becoming a success and focus on console games after that.

There really was a kidnapping scandal in Japan but the game company's name was written as [REDACTED] in the news and never known.
Everyone's just assuming that it's SEGA while it's unlikely since unlike the rest of the world, SEGA's rival in Japan wasn't Nintendo.
It's ... Namco, Capcom, Data East, and Konami. SEGA's becoming the king of arcade in Japan by 'defeating, them, not Nintendo.
